Construction element for walls and wall lining and production method of the element

ABSTRACT

Construction element for walls and wall lining comprising at least one layer of lining material ( 11 ) and one layer of lightened natural lime ( 12 ) attached to the lining material ( 11 ) by drying to form a single body.

FIELD OF THE INVENTION

The present invention relates to a construction element for walls and wall lining and production method of the element. DE10160665 represents one example of construction element, which characteristics are described in the preamble of claim

BACKGROUND OF THE INVENTION

Natural lime is known as natural hydraulic lime mortar. It is obtained by firing marly limestones in vertical ovens at a temperature of about 1000° C. A long extinguishing and maturation follows before grinding. When laying it is sufficient to mix the lime powders with water until homogeneous, soft and lump-free paste is obtained.

Natural lime has been abandoned in recent years in favour of new materials that are easier to lay and more durable, as obtained by plasticizing components.

In recent years, natural lime is being re-evaluated for a number of reasons.

First of all, as indicated by its name, natural lime is a natural product that has been known since the antiquity, in which we have placed a certain confidence in terms of non-toxicity.

Secondly, it is breathable, thus preventing moisture build-up that can make environments unhealthy.

Another reason that lime is more often used is linked to its fire resistance. It indeed has class 1 fire resistance i.e. it is classed among the less combustible materials.

In addition, natural lime has a very poor thermal conductivity of about 0.54 W/mK.

Above all, by virtue of this latter property, lime is used more and more often to produce thermal linings, i.e. exterior linings for dwellings, in order to reduce the conductivity of the coated walls. For this purpose, it is often mixed with aggregates having insulating properties, such as granulated cork, natural or artificial fibres, such as polystyrene and the like. By virtue of these mixes, limes thus composed are generally called “lightened”, in that these aggregates generally have a lower specific weight than the lime.

The use of lightened lime is however laborious, in that it requires at least 24 hours of drying under optimum setting conditions and since the thickness of each spreading layer cannot exceed 2 cm. Drying times can further increase during the winter period.

Furthermore, in attempting to lay more than 2 cm at a time, unsightly depressions and protrusions often form on vertical walls.

An insulated exterior cladding, for example, can provide for the laying of as much as 8 cm of natural lime. This means having to produce at least 4 layers.

It must also be considered that natural lime does not have a great mechanical strength, thus the laying of at least one mesh must be provided so as to prevent the formation of cracks and edge cracks. In addition, the effect of wind and of bad weather in general tends to very quickly degrade the most superficial layers of lime.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a construction element for walls and wall lining that allows the advantages of natural lime to be obtained while minimising the defects thereof, including the laying laboriousness and low mechanical strength thereof.

The object of the present invention is a construction element for walls and wall lining, according to claim 1.

Another object of the present invention is a sandwich curtain wall element substantially obtained by the above-described construction element with the addition of a further layer of lining in the free face of the layer of lightened natural lime.

Another aim of the present invention is to show a method of producing said lining element, which allows said element to be very rapidly obtained, with uniform characteristics in terms of both form and finish.

A further aim of this invention is a method of producing a lining element for walls, according to claim 9.

The dependant claims describe preferred embodiments of the invention, forming an integral part of the present description.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will become more evident in the light of the detailed description of preferred, but non-exclusive, embodiments of a lining element for walls illustrated, by way of a non-limiting example, with the assistance of the accompanying drawings, in which:

FIG. 1 represents a cross-sectional view according to the thickness of a construction element of the present invention;

FIG. 2 represents a variant of the construction element according to the same view of FIG. 1;

FIG. 3 shows a further variant of the construction element according to the same view of FIG. 1;

FIG. 4 shows another variant of the construction element according to the same view of FIG. 1.

The same reference numbers and letters in the drawings identify the same elements or components.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

According to the present invention, a lining element 1 comprises a first layer 11 of lining material, intended to remain in view, and at least a second layer 12 of lightenedlime. See FIG. 1.

According to a first embodiment of the invention, said first layer is made of so-called thin stone. The thin stone consists of a very thin slice of hard stone supported by a layer of resin, where thin means from a few tenths of a millimetre to a few millimetres.

This layer of thin stone is obtained by gluing a layer of resin, possibly supported by a fibre glass mesh, onto the surface of a natural stone ridge, such as sandstone, lava stone, quartzite, etc. Once the resin is dry, a thin layer of stone is literally torn from the ridge, thanks to the mesh attached thereto. The thin slab of stone obtained does not thus have a perfectly smooth surface but has, on the contrary, a natural roughness due to its removal from the other layers of the ridge.

The use of thin stone has been known for some time, but has always been associated with support structures defined by aluminium panels which are typically hollow on the inside, with honeycomb cavity.

The dried lime is capable of providing the necessary support to the layer of lining.

In particular, according to the present invention the attachment of the lime to the layer of lining preferably takes place thanks to the adhesion capacity of the lime itself. Thus when dried the lime is naturally attached to the layer of lining.

According to the present invention, the thin stone is supported by a layer of lightened natural lime having a variable thickness of between 1, 10, 20, 30, 40 cm or more in relation to requirements.

Hereunder, the word lime or natural lime indicates lightened natural lime.

In relation to the thickness of the layer of lime, one or more withholding net 13 may be introduced into the lime itself. See FIG. 2 for this purpose. The meshes 13 are known per se. They can be made of plastic or glass fibre.

According to a preferred production process, the layer of thin stone is laid onto a bearing surface, generally horizontally, and the natural lime is placed thereon, with the possible introduction of withholding net 13.

A thin stone slab thus has a natural stone face and a resin-coated face.

The use of suitable fixatives before laying the lime may be provided in relation to the surface roughness of the resin-coated face.

Preferred fixatives can for example be made of polyurethane, of epoxy resins, possibly bi-component.

Once the lime has been laid, it can all be left to air-dry, or kiln-dried. According to the present invention, a slab is obtained that can then be cut in relation to specific requirements, forming bricks or slabs in relation to the final size ratios.

Since, contrary to what may be thought, the thin stone slabs can possess a certain degree of flexibility, the construction elements obtainable can present a discrete curvature of the visible part, which may be concave or convex.

According to a second variant of the present invention, said first layer is made of tufa, i.e. a natural limestone.

Tufa is a particularly friable material, but has excellent properties linked to its ability to thermally insulate and store heat.

This material is used in large quantities, however due to its friability it is quarry-cut from very large blocks into thickset blocks having a thickness of not less than 5-7 cm.

In order to coat a wall with tufa it is thus necessary to use of a considerable amount of material on account of the difficulty in handling this material. This implies obvious quarrying, cutting, and transport costs as well as laying costs.

According to the present invention, said first layer 11 of the construction element can be made of tufa. The layer of lime 12 provides for the production of a sufficiently stiff support that prevents the tufa from being crushing during laying and during handling of the construction element obtained.

According to a preferred variant of the invention, the layer of tufa can be reduced to a few millimetres. Possible thicknesses range from 3-4 mm to 20 or more mm.

According to a preferred production method, a slab of tufa having a thickness S is first cut and placed on a bearing surface.

Natural lime is placed on the layer of tufa according to the methods as previously illustrated, an intermediate product 1 thus being obtained which is coincident with the that which is illustrated in FIG. 1 or 2.

Once the layer of natural lime has dried, the element obtained is turned over, bringing the layer of lime 12 as supporting element. A further layer 12′ of lime is then lay on the layer 11 of tufa. An intermediate product 1 b is obtained as shown in FIG. 3.

Once this second layer 12′ of natural lime has been dried, the element obtained is cut perpendicularly to the thickness S of the element at the median part r of the layer 11 of tufa.

Two construction material elements 1, having a thickness of S/2, are thus obtained.

According to a further variant of the present invention, another layer 11′ of tufa can be attached to the free face of the layer 12 of lime, preferably until the layer of lime has solidified, so as to form a single body. In this regard, see FIG. 4. It is indeed noted, that the element obtained forms a sort of sandwich with the lightenedlime 12 between the two layers of tufa. This variant is particularly suitable for producing curtain walls, partition walls and partitioning in general.

According to the present invention a multiple sandwich comprises several layers of lime alternated with layers of tufa.

According to a preferred production method of curtain wall elements, a multiple sandwich is preventively produced and subsequently perpendicularly cut to the thickness S of the sandwich, at the median part r of each layer of tufa, as shown in FIG. 3. A number of curtain wall elements can thus be obtained at the same time.

It is preferred that this sandwich be transported by a conveyor belt so that the cut is made horizontally, parallel to the direction of travel of the conveyor belt. The support provided by the lime itself allows layers of tufa lining having a thickness that is less than the 2 cm provided by the prior art, to be obtained.

A preferred production method of the multiple sandwich can provide for the superimposition of the upper layers once the lower layers of lime have partially dried.

Any openings for the passage of water pipes and electrical wiring conduits may be already arranged during the production step of the construction or curtain wall elements according to the present invention.

Water and electrical wiring conduits can indeed be embedded in the layer of lime, thus greatly simplifying the successive plant production steps. These solutions, for example, cannot be achieved through the exclusive use of honeycomb aluminium panels as support, in that there would be no filler material for the embedding of the conduits.

By, on the other hand, combining a layer of lining 11 with honeycomb aluminium support panels and the lightenedlime, tiles suitable for creating floors and ground surfaces can also be obtained. In this case, the preventive insertion of water conduits into the layer of lime allows under-floor heating systems to be produced.

The tufa-coated element variant is particularly advantageous due to the properties of the tufa, especially when friable, in that it is easily handled to obtain suitable shapes in situ, without the use of special tools. Consequently, thanks to the present invention, the excessive fragility of this material has been consequently been converted into a strength.

Advantageously, thanks to the present invention:

-   -   the construction elements coated in tufa are laid to form more         or less continuous walls,     -   inlays and finishes can be obtained in these walls,     -   resins, paints or water-repellents can be laid on the layer of         tufa, so as to stiffen it.

These resins and paints are known per se.

According to the present invention, the laying of the element obtained can be advantageously carried out with further lime, thus obtaining a composition of the “lime on lime” type, without the use of additional adhesives or of additional mechanical components that can involve heat bridges.

The limestone has a surface roughness such that any fixatives between the limestone and the lime can also be avoided.

After laying, the layer of lining material 11, whether of thin stone rather that tufa or ceramic or terracotta tiles, are visible.

Advantageously, according to the present invention, the natural lime is laid when already in a solid state, thus limiting the setting times resulting from the problem of the drying of the various layers of lime. In addition, the use of lime that has already solidified, allows the handling of friable materials such as thin stone or thin slabs of natural tufa, which it would not be possible to handle without a support.

In addition, the lightened lime having a specific weight lower than that of the tufa, the construction element obtained according to the present invention is lighter than a traditional block of tufa of equal dimensions. Furthermore, it has better heat-insulating properties than the simple tufa.

A further advantage provided by the present invention is that, in addition to having excellent physical-mechanical properties, the natural lime is much more economical in terms of both the objective cost of the material and in terms of transport, which is usually transported in sacks.

The honeycomb aluminium panels, which are expensive per se, have a disadvantageous weight/volume ratio, thus markedly affecting transport costs.

The use of honeycomb aluminium panels to contribute to the stiffening of the construction element described herein is also possible when construction elements of considerable size are to be produced. For example, entire walls or considerable portions thereof. According to one preferred variant of the invention, one or more withholding net 13 can be replaced by honeycomb aluminium panels.

In this case, these honeycomb aluminium panels can be interposed between layer 11 and lime 12 or within the thickness of the layer of lime 12.

According to another aspect of the invention, the combination of lightened lime and tufa allows an advantageous mix of thermodynamic characteristics, both in terms of thermal insulation and thermal capacity, to be obtained. In addition, a considerable increase of the acoustic insulation has been noted due to the strong physical-mechanical inhomogeneity of the two materials.

According to a further preferred embodiment of the invention, a construction module formed by two elements can be obtained so that the lime is internally confined and only the respective layers of lining are visible externally.

This solution is optimal, above all, in the production of removable single-block and street walls.

The elements and the characteristics illustrated in the different preferred embodiments can be combined with each other without however deviating from the scope of protection of the present application. 

1. Construction element for walls and for wall lining, comprising at least one layer of lining material (11) and one light inner layer attached to the lining material (11) by drying to form a single body, wherein said inner layer is lightened natural lime (12).
 2. Element according to claim 1, wherein said layer of lining material (11) comprises a thin slab of sandstone having a thickness of between a few tenths of a millimetre and a few millimetres.
 3. Element according to claim 2, wherein said thin slab is obtained by tearing.
 4. Element according to claim 1, wherein said lining material is tufa (limestone) having a thickness greater than 3-4 mm.
 5. Element according to claim 1, wherein said lining material is a ceramic tile or the like.
 6. Element according to claim 1, wherein a fixative is interposed between said layer of lining (11) and said layer of lightened natural lime (12).
 7. Element according to claim 1, wherein said layer of lightened natural lime (12) has a thickness greater than 1 cm.
 8. Curtain wall element comprising a first layer of lining material (11) and a second layer of lining material (11′) with at least one layer of lightened natural lime (12) interposed and dried to form a sandwich.
 9. Production method of a construction element for walls, comprising at least one layer of lining material (11) and one light inner layer attached to the lining material (11) by drying to form a single body, wherein said inner layer is lightened natural lime (12), the production method comprising at least the following steps: preparing a layer of lining (11), arranging said layer of lining (11) on a horizontal plane, spreading a layer of lightened natural lime (12), drying said layer of lightened natural lime (12).
 10. Method according to claim 9, further comprising the step of interposing at least one reinforcing mesh (13) of the thickness of the layer of lime (12) and/or of preparing a fixative on the layer of lining (11), before spreading the layer of lime (12).
 11. Method according to claim 9, further comprising the following steps after drying: turning over the element obtained, spreading a further layer of lightened natural lime (12′), drying said further layer of lightened natural lime (12′) cutting the element obtained perpendicularly to the thickness (S) of the element at a respective median part (r) of the layer of lining (11). 